reynolds



Sept. 24, 1963 H. C. REYNOLDS IMPACT WRENCH Filed April 5, 1960 INVENTOR HAROLD C. QDS

B\ HIS fifim Y United States Patent,

3,104,743 IMPACT WRENCH Harold C. Reynolds, Athens, Pa, assignor to Ingersoli- Rand Company, New York, N.Y., a corporation of New Jersey Filed Apr. 5, 1960, Ser. No. 20,180 2 Claims. (ill. 192-305) It is an object of this invention to provide an improved form of impact clutch in which the interengaging member is operable solely by air pressure.

'It is a further object of the invention to provide a simple, easily manufactured impact clutch positive in its action and very reliable.

Other objects will be in part obvious and in part pointed out hereinafter.

In the drawing showing an improved and preferred embodiment of my invention,

FIGURE 1 is a side view of an impact wrench provided with an impact clutch, the clutch and its housing being shown in longitudinal central section along the line 11 of FIG. 2 looking in the direction of the arrows;

FIG. 2 is a cross section of the clutch along the line 22 of FIG. 1 looking in the direction of the arrows;

FIG. 3 is a perspective view of the operating valve, partly in section, to show the ararngement of ports and passages therein;

FIG. 4 is a section of the valve taken along the line 44 of FIG. 3, looking in the direction of the arrows;

FIG. 5 is a section of the valve taken along the line 5-5, looking in the direction of the arrows in FIG. 3; FIG. 6 is a section of the valve along the line 66, looking in the direction of the arrows in FIG. 3; and

FIG. 7 is a longitudinal section of a part of an impact tool showing an alternative form of valve. The section may be considered to be taken along part of the line 1-1 and is viewed in the direction of the arrows.

Referring to the drawings the impact clutch is shown as part of a form of impact wrench which has for its motive element an inclosed motor 16 of any suitable pneumatic type, and controlled by a conventional throttle valve 12 connected to suitable air line 14 from a source of air under pressure (not shown). The clutch 16 is suitably connected to the motor 10 and is driven by the motor shaft 18. The clutch generally consists of a hammer element 20 and an anvil 22 adapted to be interengaged by a controlled dog 24. As is usual in such tools anvil 22 is provided with a spindle 26 extending through a nose portion 28 of a casing 30 which houses clutch 16. Spindle 26 is suitably formed at its end 32 to retain a socket 34 in this instance, for engaging the work which may be the nut 36 of a bolt 38.

Hammer 20 is mounted on the end of a shaft 40 of a spindle driven by drive shaft 18, and is adapted to be driven by that shaft through a cone clutch 42 splined to the end of the shaft 40 and held in engagement with hammer 20 by a Belleville spring 44.

At its forward end, hammer 20 is rotatable on a member 43 supported in a bore in and coaxial with the anvil 22. Member 48 has a square portion 52 imbedded in anvil 22 to prevent rotation of member 48 .with respect to the anvil. Member 48 is a valve and the portion rearward of 5-2 is cylindrical and extends into an axial bore 54 in hammer 20.

"Ice

Dog 24 is in effect a piston slidable in a bore 56 substantially parallelwith bore 54 and located in a wing 58 of hammer 20. There is provided a flange 59 on the dog 24 having pressure faces 60 and 62 for reciprocating dog 24 freely in bore 56. Within bore 56 there is formed a pressure chamber 61 within which the flange 59 reciprocates, there being a bushing 64 extending in the lower section of bore 56 in which fits the main body of dog 24 rather loosely. At the other end of dog 24 bore 56 terminates at a shoulder formed by a reduced bore 66.

Valve 48 is adapted to supply air under pressure to exert pressure alternately on the pressure faces 60 and 62. For this purpose, ports 68 and 70 are provided diametrically opposed in valve 48, and spaced apart to register with ports 72 and 74, respectively, leading to chamber 61. Ports 68 and 76 communicate with a central passage 76 in valve 48 which is connected by passage means 78, 80 to the air supply at the throttle valve 12. This passage means comprises a passage 78 in the casing of motor 10 and a central longitudinal passage 86 leading through drive shaft 18 and shaft 41 Leakage around the end of the shaft 40 is prevented by an O-ring 82. The end of chamber 61 opposing the end receiving pressure air is exhausted by a port 84, in the valve 48, leading to atmosphere.

A lug on anvil 22 is formed as at 86 by cutting away to a depth corresponding to the throw of the dog 24, that part of the head of anvil 22 which will leave two spaced apart striking surfaces 88 curved to fit the cylindrical wall of dog 24.

.To counterbalance the wing 58 which contains dog 24, hammer 20 is provided with two more wings 90 and 92 which will also provide additional weight.

In operation, hammer 20 is adapted to rotate with dog 24 down to contact lug 86 of anvil 22. At the point of contact between the dog 24 and the lug 86, as shown in FIGURES 1 and 7, the hammer 20 and the valve 48 are positioned so that the port 70 of the valve 48 registers with the port 74. At this position, as shown in FIGURES 1 and 7, the port 74 extends in part beneath the pressure face 62. It may be seen that air will be admitted in port 74 to push against the pressure face 62. The air pressure against the pressure face 62 will cause the dog 24 to rise to disengage and ride over lug 86. Dog24 is then depressed again until it reaches approximately its next strikmg position.

Thus as will be seen in FIG. 2, with the dog 24 in contact with lug 86, port 74 registers with port 70 of the valve to admit air into the lower portion of chamber 61 to exert pressure on the lower pressure face 62 to push dog 24 up. This registry of ports continues until dog 24 passes beyond lug 86 whereupon shortly thereafter port 72 will register with port 68 in the valve to admit air into the upper portion of chamber 61 to exert pressure on the upper pressure face 60 to again depress dog 24.

At this time, air from the lower portion of chamber 61 is exhausted through port 74 and exhaust port 84 to atmosphere.

In some instances, the exhaust port 84 can be dispensed with as shown in FIG. 7, because the upper and lower portions of chamber 61 are small and the fits around dog 24 are not particularly tight. The instant the air supply isc ut off the pressure in these portions of chamber 61 drops.

The apparatus has been described as being provided with a cone clutch 42, as the drive connection between motor 10 and clutch 16. The purpose of this is to reduce the great shock on the connection between the motor and the hammer. In time, splined connections are apt to break because of shock impacts by stripping the teeth. This is particularly noticeable if the motor is large and m9 7 powerful and the connection cannot be made correspond- '(d) a dog reciprocably disposed in said cylindrical ingly strong. chamber to engage said anvil lug,

Thus are accomplished among others the objects and (e) opposed pressure faces on said dog in said cylinadvantages hereinbefore referred to. drical chamber,

I claim: 5 (f) said opposed pressure faces cooperating with the 1. A clutch for pneumatic impact Wrenches and the walls of said cylindrical chamber to define two preslike comprising: sure chambers in said cylindrical chamber,

,(a) arotatable anvil havingalug for receiving impacts, (g) ports in said hammer leading to each of said (b) a rotary hammer operably associated With said pressure chambers,

rotatable anvil, (h) a valve rotatably mounted in said hammer and i ,(c) said hammer being provided with a. cylindrical actuated by said anvil,

chamber, (1) ports in said valve associated with said hammer (d) a dog reciprocably disposed in said cylindrical ports to conduct air from a suitable supply to said: chamber to engage said anvil lug, valve for distribution thereby to said pressure cham- (e) opposed pressure faces on said dog in said cylinhers, and

drical chamber, (j) said valve ports being positioned'in said valve to (f) said opposed pressure faces cooperating with the alternatively selectively conduct air to said pressure Walls of said cylindrical chamber to define two preschambers to activate only one pressure chamber at sure chambers in said cylindrical chamber, and a time to cause said hammer dog to reciprocate. (g) means for alternatively selectively conducting air 1 to said pressure chambers to activate only one pres- References Cited in the file of this patent sure chamber at a time to cause said hammer dog to H reciprocam UNITED STATnS PATENTS 2. A clutch for pneumatic impact Wrenches and the 1,729,173 Marfaing Sept. 24, 1929 like comprising: 2,476,632 Shafi July 19, 1949 (a) a rotatable anvil having a lug for receiving impacts, 2,693,867 Maurer Nov. 9, 1954- (b) a rotary hammer operably associated with said 2,784,818 Maurer Mar. 12, 1957 rotatable anvil, 2,821,276 Reynolds Jan. 28, 1958 (c) said hammer being provided with a cylindrical 2,822,072 Goss Feb. 4,1958

chamber, 

1. A CLUTCH FOR PNEUMATIC IMPACT WRENCHES AND THE LIKE COMPRISING: (A) A ROTATABLE ANVIL HAVING A LUG FOR RECEIVING IMPACTS, (B) A ROTARY HAMMER OPERABLY ASSOCIATED WITH SAID ROTATABLE ANVIL, (C) SAID HAMMER BEING PROVIDED WITH A CYLINDRICAL CHAMBER, (D) A DOG RECIPROCABLY DISPOSED IN SAID CYLINDRICAL CHAMBER TO ENGAGE SAID ANVIL LUG, (E) OPPOSED PRESSURE FACES ON SAID DOG IN SAID CYLINDRICAL CHAMBER, (F) SAID OPPOSED PRESSURE FACES COOPERATING WITH THE WALLS OF SAID CYLINDRICAL CHAMBER TO DEFINE TWO PRESSURE CHAMBERS IN SAID CYLINDRICAL CHAMBER, AND (G) MEANS FOR ALTERNATIVELY SELECTIVELY CONDUCTING AIR TO SAID PRESSURE CHAMBERS TO ACTIVATE ONLY ONE PRESSURE CHAMBER AT A TIME TO CAUSE SAID HAMMER DOG TO RECIPROCATE. 